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Bryophytes lecture
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BOTANY 201 LaboratoryDepartment of Biological Sciences
College of ScienceUniversity of Santo Tomas
� Moist-loving plants
� Pioneer species
� Small plants that has chlorophyll a & b, cell walls made up of cellulose, motile sperms & starch (storage)
Lack well-developed vascular tissues → absorb water � Lack well-developed vascular tissues → absorb water by capillarity
� Lack true roots, stems & leaves
� Gametophyte – dominant; perennial
� Sporophyte – short-lived; unbranched; produces sporangium
� Heteromorphic Alternation of Generation
� Gametophyte generation:� dominant stage
� Free-living & photosynthetic
� Sporophyte generation:� Sporophyte generation:� short-lived
� attached to and dependent on the gametophyte for nourishment → parasitic to the gametophyte
Character Thallophyte Brophyte
Plant Body •single cells or filament of cells
•blocks or sheets of cells forming a parenchymatoustissue
Gametangia •unicellular and lacks a protective jacket of sterile cells
•multicellular and have a protective jacket of sterile cells
cells
Primitive Features Advanced Features
• Usually have no lignin• Small, low-lying, and generallymoisture loving plants• No roots, only filamentousrhizoids
• Have multicellular sex organs (i.e.:gametes are enclosed by sterilejacket cells)• Are parenchymatous, notfilamentousrhizoids filamentous• Retain the zygote within thefemale sex organ & allow it todevelop into an embryo there• Have cutin on the plant andspores
LIVERWORTS HORNWORTS MOSSES
� Hepatics or liverworts
� rhizoids are always unicellular� Thallus are dichotomously
branched and exhibits dorsiventrality:� upper side – photosynthetic
(chlorenchymatous cells & air chambers)(chlorenchymatous cells & air chambers)
� lower side – for storage & non-photosynthetic (scales & rhizoids)
� Gametophytes are lobed & bilaterally symmetrical1. Leafy2. Thallose
� Unstalked sporangia� Reproduce asexually
� Thallose liverwort
� Gametophyte:� Flat, ribbon-like
� Perennial; dichotomously branchedbranched
� Unisexual
� Gametophores:� Archegoniophore
� Antheridiophore
Male Female
Gemma – multicellular asexual reproductive units
� Hornworts – long horn-shaped sporophytes
� have the simplest gametophytes of the Bryophyta
� small, green thallus plants with little differentiation of vegetative tissues.
� antheridia are located in roofed chambers in the upper � antheridia are located in roofed chambers in the upper portion of the thallus.
� archegonia are embedded within the thallus.
� sporophyte is different from that of the Hepaticae.
� foot embedded in the thallus serves an absorbing organ. The sporangium is an upright elongated structure.
� Mosses have specialized cells that conduct water and others that conduct photosynthate.
� Gametophytic generation – dominant; has two growth stages:� creeping filamentous stage (the protonema) from which is
developed,The moss plant with an upright or horizontal stem bearing small developed,
� The moss plant with an upright or horizontal stem bearing small spirally arranged green leaves.
� Sporophyte – dependent on the gametophyte for survival.
� have disc shaped chloroplasts, lack pyrenoids and have stomata
� Rhizoids are found at the base of the stem
� Gametangia occur at the tips of either the main or lateral branches
Moss Gametophyte
Moss Sporophyte